A never-before-seen species of giant sea turtle was recently discovered in Spain. With a body length of more than 12 feet, this is the largest turtle species ever found in Europe.

Named Leviathanochelys aenigmatica, the species was identified from pelvis and shell fragment fossils found in Cal Torrades in northeastern Spain. The genus, Leviathanochelys, was chosen for the Biblical marine beast, Leviathan. Researchers believe the turtle lived during the Cretaceous period, almost 83.6 to 72.1 million years ago.

Many paleontology discoveries are stumbled across, and this discovery was no exception. A hiker in the Pyrenees mountains stumbled across the bone fragments.

The largest living marine turtle, leatherbacks (Dermochelys coriacea) reach almost 6 feet long, whereas L. aenigmatica were twice that size. The world’s largest turtle, however, remains the Archelon ischyros, whose fossilized remains were first found in South Dakota in 1895 and measured 15 feet long.

Read the full study here.